Performance Indicators of LED Display

Better  understanding of the main performance indicators of the LED display

In 1998, after five years, the special committee in the LED display (now the industry standard for China LED Display Optical Society Chapter) efforts of the organization, "LED display test methods" (hereinafter referred to as the "standard") upcoming release implementation. To correctly guide the user to understand the performance of the LED display, the specification of the LED display market has a very important significance. In order to better implementation of the standards, make the following recommendations.

1. Maximum brightness

    Discussed at the end of last year, the industry "standard", this important performance for the "maximum brightness" did not give a clear characteristic requirements, which is consistent with GB/T1.2-2002. "Standardization Guide Part 2: The the standard normative technical elements of the content of the method for determining" "5.4.3 value determined by the supply-side" mentioned: "If you allow the diversification of product exist, product Some characteristic values do not have to make provisions (although these features have a significant effect on product performance). " Because of the use of the LED display environment vastly different, illuminance (that is, the general said ambient light) is not the same, "for the most complex products, as long as the test method specified in the standard, by the supply-side to provide a copy of the performance data (product information) list given specific performance requirements better, "than the standard. These are in line with international standards, but this also resulted in a competing bid unrealistic comparisons with each other, users of this without understanding, resulting in maximum brightness requirements in many tenders often much higher than the actual need. Therefore, it is recommended that in order to guide users to the correct understanding of the maximum brightness LED display performance, the industry is necessary to give a guidance: in some cases, the use of the environment under different illumination, the brightness of the LED display what value to meet the requirements.

2. Gezer main wavelength error

    Error indicators of the primary colors dominant wavelength from the the "Gezer wavelength error" changed to "the Gezer main wavelength error" This indicator is better able to explain what characteristics LED display. A dominant wavelength of the color corresponds to the human eye the color tone of the color observed is a psychological quantity, is an attribute of color distinguishable from each other. The standard specifies performance requirements of the industry, literally, the user is unable to understand that it is an indicator to reflect the color of the LED display uniformity. Therefore, is to guide users to first understand the terminology, and then understand the indicators? To first to understand from the customer's point of view and understanding of the LED display, and then presents the user can understand the performance characteristics of the easy-to-understand? As mentioned earlier the GB/T1.2-2002 (Standardization Guide Part 2 standard normative technical elements content determination method "on product standards developed one of the principles that" performance principle ":" as long as possible required performance characteristics should be expression without expressed in the design and characterization, this approach to technology development left the biggest room "the" Gezer main the wavelength error "is one such design requirements," color uniformity instead, there is no limit what wavelength of the LED on the user, as long as you ensure the LED display color is uniform, without regard to what technical means to achieve as large as possible is left to the technical development room which is of great benefit to the development of the industry.

3. Duty

     As stated above. "Performance principle" as long as possible, the requirements should be performance characteristics to express, without design and characterization to express this approach to technology development, leaving the largest room ". We believe that the "duty cycle" is purely a design technology requirements, and should not be used as a performance standard LED display products; everyone understand which users will care about the display drive duty cycle, they care about is the effect of the display, instead of our technology; why their own technical barriers to limit the industry's technology development?

4. Refresh rate

    From the "standard" measurement method, seem to ignore the real concerns of users, it is also not well taken into account the various driver IC manufacturers, drive circuit and in different ways, resulting in the difficulty of the test. For example, the full-color screen Shenzhen Stadium tender brought many questions, the expert sample test, the test of this indicator. "Refresh rate" of a reciprocal of the time required for screen display, the display as a light emitting light source, that is, the blinking frequency of the light source. We can test directly with a similar sense of light frequency meter instrument display light source flicker frequency to reflect this indicator. We've done this test oscilloscope measurement of any color of the LED drive current waveform to determine the refresh rate, measured in the white field, 200Hz; three gray low gray level, the measured frequency up more than 10 kHz, while both in the white field, 200,100,50 level grayscale metering the source flicker frequency are 200Hz PR-650 spectrometer measurements;

    Above points just for a few LED display features a simple description, there are many bidding encountered working life "mean time between failures" and so on, there is no test method in a shorter LED display meets the requirements of the stability, reliability or life; should not stipulate that these requirements within the time confirmed. Producers can guarantee, but can not replace the requirement, it is a business concept, the concept of the contract, rather than a technical concept. Industry Association, this should be a clear view for users, producers, as well as the industry as a whole will be very beneficial.